The present invention is in the field of power tools, and is more particularly related to accessories for use with electrical motor driven tools.
It is common practice in tool configurations to include a substantially planar work surface for supporting a workpiece with respect to a cutting element. For example, a table saw includes a planar surface with an electrical motor driven circular saw blade adapted for rotary motion about an axis parallel to the work surface. As another example of a common power tool, a drill press typically includes a substantially planar work surface, and a cutting element adapted for rotary motion about an axis perpendicular to the work surface, with the bit also being selectively positionable along that axis. In such configurations, a workpiece may be positioned by hand with respect to the cutting element, and then the cutting element activated to achieve a desired cutting or tooling operation.
In many applications, it is desirable to perform a number of identical cutting operations at uniformly spaced locations on a workpiece. For example, a succession of uniformly spaced holes may be made in a workpiece, with the respective holes extending along a desired axis. As a further example, a finger joint, or box joint, may be made to join the ends of two workpieces made of wood, for example where cuts in the ends of the pieces define "fingers" in each end which are appropriately sized and positioned to permit interleaving. Typically, finger joints require precisely positioned and precisely dimensioned fingers.
In circumstances where such cutting operations are desired on a large scale, for example in a mass production manufacturing facility, special machine assemblies may economically be configured to accomplish the precision cutting operations. However, in the confines of a typical home work shop, for example, where economics permit only limited sophistication in the available tools, the complex and precise machining operations must be accomplished with relatively inexpensive equipment. Often specialized jigs may be assembled to be used in conjunction with a readily available and inexpensive tool.
In the prior art, finger joints, for example, may be made in the manner disclosed in the text "Tage Frid Teaches Woodworking", published by the Taunton Press, Inc., Newtown, Conn., 1979, pages 90-93. According to this prior art teaching, a finger joint may be made with a table saw having a dado head, where the workpiece is manually positioned so that each finger-defining cut is made individually, following a manual re-positioning of the workpiece. While that method does provide a succession of cuts which may be suitable for finger joints, the successful accomplishment of such a joint requires precisely located and dimensioned cuts which are extremely difficult to make with the relatively simple jig disclosed. That jig consists of a plywood member affixed to a miter gauge on the surface of a circular saw. The plywood member includes at its base a slot which is precisely matched to the desired finger width. A guide pin the width of the slot extends outwardly from that slot. Using the jig as a support for the workpiece, the first cut in the workpiece is made after positioning the workpiece one "finger width" from the pin. Thereafter, the remaining cuts are made after successively positioning the workpiece to overlie the guide pin, one finger at at time. However, with this configuration, any error in the spacing of the cuts, is cumulative, so that the resultant finger joint is highly likely to provide a relatively poor fit, and thus a poor finger joint.
It is an object of the present invention to provide an improved accessory apparatus for use with a power tool. Another object of the present invention is to provide an improved accessory for use with a power tool which permits the generation of a succession of cuts which are substantially uniformly spaced along a reference axis.